This site is a veritable treasure trove (Venerable Red Dragon level treasure trove) of helpful generators…
Names… encounters… whole dungeons… adventures… If you don’t know about Donjon RPG Tools, you need to check them out.
Be prepared, though… it’s a rabbit hole, and it’s easy to climb way way down into it.

Pre-fab critters, complex opponents — or occasionally allies — at various Challenge Ratings. All you have to do is choose the right CR and drop it into your game. So if you’re looking for a friend or foe that’s just a little different, check out these things.

Do you need a site with a few new challenges for your players? Are your adventurers facing a long trip with nothing to do? Do you want to add excitement to your next dungeon? Check out the Vicious Venues.

I know that when I’m running an adventure, I’m sometimes a little… shall we say … background details light… Something that even after nearly 40 years of gaming and running games, I know I need to get back on track with.
I used to be much better at it, and need to start again…
With that in mind… This series could help with that.